Roth IRA & 401k tax strategy question

I have a Roth IRA and then a taxable 401K. From a tax strategy perspective, would I be better off allocating assets with probable higher capital gains (i.e. small cap stocks) in my Roth IRA with tax-free distributions while allocating assets with lower probable capital gains (i.e. large cap stocks) in my 401K that will have taxable distributions?